[PATCH net 3/5] idpf: account for VLAN header when parsing RSC packet header

[Tony Nguyen <anthony.l.nguyen@intel.com>]

From: Joshua Hay <joshua.a.hay@intel.com>

While parsing the header of a Receive Side Coalesced (RSC) packet, check
if a VLAN tag is present and adjust the header parsing accordingly.
Otherwise, Rx TCP traffic is completely broken for any VLAN interface
whose underlying interface has RSC (rx-gro-hw) enabled.

We only need to worry about one VLAN header since Rx packets with
multiple VLAN headers are not candidates for RSC.

Fixes: 3a8845af66edb ("idpf: add RX splitq napi poll support")
Signed-off-by: Joshua Hay <joshua.a.hay@intel.com>
Reviewed-by: Emil Tantilov <emil.s.tantilov@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Samuel Salin <Samuel.salin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/idpf/idpf_txrx.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
index 9ba9c2952d78..4311ffa30bb1 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
@@ -3299,6 +3299,7 @@ static int idpf_rx_rsc(struct idpf_rx_queue *rxq, struct sk_buff *skb,
 		       struct libeth_rx_pt decoded)
 {
 	u16 rsc_segments, rsc_seg_len;
+	u16 l3_start = 0;
 	bool ipv4, ipv6;
 	int len;
 
@@ -3321,7 +3322,10 @@ static int idpf_rx_rsc(struct idpf_rx_queue *rxq, struct sk_buff *skb,
 	NAPI_GRO_CB(skb)->count = rsc_segments;
 	skb_shinfo(skb)->gso_size = rsc_seg_len;
 
-	skb_reset_network_header(skb);
+	if (unlikely(eth_type_vlan(skb->protocol)))
+		l3_start = VLAN_HLEN;
+
+	skb_set_network_header(skb, l3_start);
 
 	if (ipv4) {
 		struct iphdr *ipv4h = ip_hdr(skb);
@@ -3329,7 +3333,7 @@ static int idpf_rx_rsc(struct idpf_rx_queue *rxq, struct sk_buff *skb,
 		skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
 
 		/* Reset and set transport header offset in skb */
-		skb_set_transport_header(skb, sizeof(struct iphdr));
+		skb_set_transport_header(skb, l3_start + sizeof(struct iphdr));
 		len = skb->len - skb_transport_offset(skb);
 
 		/* Compute the TCP pseudo header checksum*/
@@ -3339,7 +3343,7 @@ static int idpf_rx_rsc(struct idpf_rx_queue *rxq, struct sk_buff *skb,
 		struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 
 		skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
-		skb_set_transport_header(skb, sizeof(struct ipv6hdr));
+		skb_set_transport_header(skb, l3_start + sizeof(struct ipv6hdr));
 		len = skb->len - skb_transport_offset(skb);
 		tcp_hdr(skb)->check =
 			~tcp_v6_check(len, &ipv6h->saddr, &ipv6h->daddr, 0);
-- 
2.47.1